The present invention relates to a diagnostic method and a diagnostic means used in carrying out the method.
In certain circumstances it is desirable but difficult to prove the existence of a medicament in its surroundings in and on its way through the digestive apparatus.
Conventional methods use capsules, which are labeled with radioactive isotopes. This certainly facilitates the finding of the capsule, but it subjects the examined person to radiation, which should be avoided.
Another method tested, by means of magnetic resonance imaging (MRI), shows the existence of a tablet shown by a negative contrast agent (iron oxide+ barium) in the digestive apparatus, this tablet being shown as a black silhouette against a white background of the conventional liquid positive MRI-contrast agent Magnevist enteral.
This method has a drawback, since even if it is easy to visualize this black tablet in the ventricle (stomach) in a white sea of liquid contrast agent, this very contrast agent, when being transferred to the small intestine, apparently is mixed with other digestive liquids, which results in an uneven, streaked filling of the small intestine, the tablet also being dissolved too quickly. Thus, an indication of the existence of the tablet is not possible. Various efforts to make the positive contrast agent more paste-like have not yielded any satisfactory results. Examinations with Magnevist enteral and a negative contrast agent, i.e. an agent which is black in an MRI-display, require, that the stomach is purged before the examinations.
U.S. Pat. No. 3,939,259 teach how to fill a capsule with tablets and delay the release of medicaments by a layer of beeswax.
Barium sulphate and iron oxide in a water solution are used as negative contrast agents according to U.S. Pat. No. 5,323,760.
WO 94/03210 relates to oils, used as positive contrast agents.
Various useful and also advantageous details are individually known through these publications, but they are not combined in a particular way to speed up a diagnosis and make it more reliable, and so clear and simple that certain preparatory measures, such as purging, completely or partially can be dispensed with. Also no efforts apparently have been spent to develop a simple, variable construction, which is easy to adapt to various diagnostic requirements and desires. Also, it has not been found, that so far there has been a generally expressed desire to design a capsule having tracer functions and which can be charged with an optional module, which contains a substance to be examined.
The object of the present invention is to counteract and as far-reachingly as possible overcome the above-mentioned drawbacks. Additional objects comprise the development of the state of the art in this field in various respects.
These objects are achieved in accordance with the invention by designing a diagnostic method of the type described in the specification.
A negative MRI-contrast agent Abdoscan is on the market. This agent is mixed with water to a water solution, which, when it has been swallowed, becomes pudding-like in consistency in the digestive apparatus and fills e.g. the small intestine relatively uniformly, which substantially facilitates the finding of the white signal capsule in this uniform black sea of contrast agent. This is an obvious advantage compared to said liquid positive, i.e. white, contrast agents.
The following problem appeared; to develop a capsule, which through a positive contrast agent filling is clearly visible in a negative contrast agent and which only in the lower part of the digestive apparatus releases the substance to be examined and also is not toxic. This substance, i.e. the cargo portion, is allowed to be dissolved depending on its composition, which varies from substance to substance, in interaction with the biochemical environments in the body in various places along the movement path.
It has been found that certain deep-sea fish oil capsules on the market yield an excellent positive contrast in MRI, i.e. gives a white picture. Other natural or synthetic organic non-toxic substances may also be used.
However, such capsules are dissolved too quickly, i.e. already in the stomach and also, they have the negative property in the stomach of being lighter than water. Thus, they float on top of the contents of the stomach and do not reach the lower outlet of the stomach.
Consequently, two such capsules are wrapped in a mixture of iron oxide+ barium sulphate powder in an empty gelatin capsule and two deep-sea fish oil capsules are chosen, since the signal picture which only one capsule gives, may look like the body""s own structures, e.g. fat. In case the MRl-picture shows the two Inner capsules In front of each other, only a bright white point is visible. In order to decide, whether this is the capsule, the next picture is taken with a 90xc2x0 angle in relation to the previous one and then, In the same plane, two bright white points, having the same size, are visible, obviously a picture of the capsule and not one of the body""s own structures. In principle or alternatively, if is possible to choose such an oblong and/or a rectangular and/or an oval, inner capsule shape that, when said pictures are taken from different angles always at least one picture is obtained, which clearly differs from more common own structures of the body. As far as possible, in order to avoid taking pictures from different angles with great reliability and speed are able to identify the position of the capsule, it is also possible to give the capsule an asymmetrical shape as regards its contents in such a way, that one capsule side or end always tends to sink first, because this side or end contains substances having a larger weight and density, respectively. Alternatively, a small air inclusion can serve the same purpose. An iron oxide is chosen due to the fact that this compound, because of its negative (black) MRI-picture, yields an increased contrast around the positive (white) picture, which substantially facilitates the determination of its position. Barium sulphate is added because this compound substantially facilitates the displacement of the capsule through the force of gravity through the stomach and into the small intestine during the time when the patient, between the picture takings, is up and moves about. Tests without barium sulphate have shown that the capsule then is too light-weight, flows on top of the contents in the stomach and does not reach the small intestine within several house. Also, barium sulphate has a negative contrast effect, i.e. it gives a black picture in MRI.
Alternatively it is possible to put the signal substance in e.g. a gelatin capsule, which is wrapped up in a shell, which consists of a mixture of solid paraffin and barium sulphate.
It was found, that this functioned properly. An excellent contrast is seen between the two white oil capsules and the mixture of iron oxide and barium sulphate with its negative (black) MRI-picture and between the positive substance and the signal-negative shell respectively, which latter consists of paraffin plus barium sulphate.
In the human body there are no structures, which yield such a similar signal pattern in MRI, which substantially facilitates the finding of the capsule.
Also, the capsule is now so heavy, that it finds its way by itself to the lower outlet of the stomach.
With regards to the dissolution which is too quick, beeswax does not melt or is not dissolved at body temperatures. Thus, the dry gelatin capsule is provided on its outer side with liquid beeswax and has let the beeswax cool. The capsule is still sufficiently heavy to sink, thanks to the included barium. However, thanks to the beeswax, it has not even been dissolved when it reaches the anal opening, which is perfect from the point of view that it then also is not able to influence the examination of the substance, which is to be examined. Instead of beeswax, it is possible to use a layer, which consists of a mixture of solid paraffin (paraffinum solidum) and barium sulphate in order to obtain a protection of the capsule and, at the same time, the barium sulphate contributes to the necessary weight.
The substance to be examined is wrapped up in or is mixed with solid paraffin (paraffinum solidum). This solid paraffin portion constitutes the cargo portion itself, i.e. that portion, which is optional and can be united with the trace portion of the capsule. The release/dissolution takes place slowly or at a certain pH-value. It is done by coating the substance to be examined with a pH-sensitive substance. This method has been tested during several decades by the pharmaceutical industry and is used by routine in certain pharmacological preparations. Thus, the method allows a utilization of all this experience, how medicaments are to be mixed with paraffin in order to be released slowly and consequently in a careful way, or put in another way, intentionally during a longer time in order to provide the same medicament concentration during a long time.
Instead of beeswax another non-toxic substance can be used, which melts or dissolves only at higher temperatures than the temperatures of the body, e.g. at 40-50xc2x0 C., and which at least during a sufficiently long time is able to resist the liquids in the body without dissolving in the wrong intestinal section and with that effect respectively, that it is dissolved in the proper intestinal section and also during a long time.
Tests have shown, that it is possible to indicate the capsule all the way from the stomach and through the entire small intestine and also in the colon in its section close to the anal opening.
The present invention is not limited to what has been stated above, which only is to be considered a non-limiting embodiment, which can be modified and supplemented in an arbitrary fashion within the scope of the inventive idea and the following claims respectively.
Instead of paraffin other substances can be used, e.g. waxes plus non-toxic substances heavier than water instead of barium sulphate.
The substance to be examined can either be included in the outer capsule/the outer shell in the form of a separate capsule (the cargo capsule) or be mixed with the chemically inert substance of the shell.
It is found that a capsule, according to the invention, gives a clear signal picture against the used contrast agent, that despite small amounts of substances remaining in the stomach and the intestines, the otherwise mandatory purging before the examination is not required. This results not only in a substantial relief for the patient, who avoids the inconvenience of having at least one day lost due to the purging, but also in another advantage. A purging leads to an increased mobility in the intestines. This increase mobility is a substantial drawback during MRI-examinations, since the picture taking per se takes time (reminding one of the old-fashioned photographing, when it was necessary to stand absolutely still for a long period of time in order to obtain a shape picture). However, it is not possible to stop the movement of the intestines by sheer willpower. On the other hand, the intestines hold substantially steady, if no purging is used and one keeps fasting from the evening before the examination and then in the morning swallows the contrast agent and the capsule, which provides excellent, sharp pictures despite certain small remaining amounts of substances in the stomach/intestines.
None of the other described diagnostic means has had any substantial medical impact. None of them is said to be used commercially despite the fact, that these means have been known for several decades.